Teleprinter



Adigel TELEPRINTER R. D. SALMON Filed March 5, 1956 2.0. SALA/10N @M/wf Patented Aug. 16, 1938 UNITED STATES TELEPRINTER.

Reginald Dennis Salmon, Croydon, England, as-

signor to Creed and Company Limited, Croydon,

England Application March 5, 1936, Serial No. 67,255 In Great Britain June 21, 1935 1 Claim.

This invention relates to teleprinters and more particularly to means for controlling the speed of operation thereof.

Trac requirements for teleprinters used on 5 news services iiuctuate over Wide limits. In order to meet the requirements of the service during periods when the market is varying rapidly it is necessary to provide teleprinters that can operate at high speeds. It has therefore been necessary to operate such teleprinters at high speed all the time, although for most of the time a slow speed only is necessary. The wear and tear of the machines and the necessary maintenance are unduly increased in order to provide for occasional requirements.

This arrangement besides being wasteful, does not allow the highest possible speed being attained, because the maximum speed of operation is determined by the speed at which the machine can safely be run continuously.

According to this invention, a teleprinter is provided with governors able to keep the speed constant at two diierent values, respectively and with a two way switch for causing the speed to be kept at one or other of the two values.

The switch is actuated to keep the teleprinter at the higher speed during rush periods and at the lower speed during normal operation. As only the transmitting station is aware of when a rush period occurs the switch is arranged to be operated under the control of the transmitter and preferably the actuation of the switch is effected by two signals in the upper case sent from a keyboard transmitter in conjunction with a monitoring printer.

This arrangement has the advantage that the slow speed can be set lower than the present operating speed, being Xed to provide for normal traiiic requirements, the high speed can be set 40 above the present operating speed, being limited only by the maximum safe operating speed of the printer for short periods, whilst greater traffic capacity is thus ensured without increase in maintenance costs.

The preferred manner in which the invention is to be carried into effect will be understood from the following description taken in conjunction with the accompanying drawing in which,

50 Fig. 1 represents a diagrammatic View of a device used in carrying out the invention, which embodies two separate governors in the one construction;

Fig. 2 is a view at right angles to that of Fig. 1

55 showing also the circuit of the motor and the position therein of the switch for changing from one speed to another, whilst Fig. 3 is a circuit diagram showing how the switch causes one or other governor to control the speed of the motor.

A device as shown in Fig. 1 is fixed to the shaft of the motor driving the receiving teleprinter and an exactly similar device to the shaft of the motor which drives the transmitter and the monitoring teleprinter associated therewith. This device comprises two separate governors mounted on a disc D but in different planes. As shown each of these governors is of the type described in my U. S. Patent No. 1,868,616, issued July 26, 1932, in which a spring F or S stretching across the centre 15 of rotation of the disc is attached to the centre of gravity of a contact arm to close contacts A or B whilst the speed is below a particular value, and open those contacts when the speed reaches that value. Contacts B are arranged to open at a 20 slow speed and contacts A at a high speed. The fixed parts of contacts A and B are connected to conducting rings A and B respectively on the reverse side of disc D. The parts of contacts A and B movable according to the speed of disc D are connected together and to a contact block C conductively connected to a third conducting ring C. Brushes A, B", C make connection with the rings A', B', C respectively. The connections from the mains supply to the motor M are made 30 through contacts A, and through a normally closed control switch S and contacts B in parallel,

a high resistance R being connected across all contacts.

The operation of the device will be clearer from Fig. 3 which shows the connections schematically. When a certain speed has been reached contacts B open, but with control contacts S closed, this has no effect and the speed of the motor increases until contacts A open, whereupon the speed is kept constant.

When the control switch S is open, the speed is kept constant at the lower value by the operation of contacts B, and the speed never reaches a value at which contacts A open.

It is clear that the control switch S could be arranged normally open so that the motor would run at the slower speed until the control switch is operated.

The control switch S is operated in one direction when a particular character in the upper case is received and in the other direction When another character in the upper case is received. The receipt of either character causes a function lever to be selected and operated in Well known manner and the operation of such function lever closes or opens the switch as the case may be.

The arrangement for controlling the switch S by the selecting portion of the receiving printer is illustrated diagrammatically in Fig. 2. In this gure, P designates the printing mechanism and E the selecting mechanism associated with the printer. Broken line K indicates the control lever connection for opening or closing switch S in response to certain operations of selector E by signals incoming over line L.

It is to be understood that the invention isv not limited to the particular embodiment described. For example, the governors employed may be of any type desired, and the two governors may be mounted independently instead of being incorporated in the one device.

What is claimed is:

Printing telegraph receiver comprising selecting and printing mechanisms, a motor for driving such mechanisms, a disc xed to the shaft of said motor two speed governors mounted on the said disc, contacts on each governor arranged in series in the motor circuit, the said contacts being open when the speed reaches a given value,- different for each governor, switch contacts shunting when closed the governor contacts that open at the lower speed, and means actuated under the control of said selecting mechanism responsive to particular received signals, for opening and closing said switch contacts.

REGIN ALD DENNIS SALMON. 

